Sound-box mounting



C. SCRABIC.

SOUND BOX MOUNTING.

' APPLICATION FILED MAR. 25. 1920.

PatentedSept. 27, 1921.

2 SHEETS-SHEET I.

C. SCRABIC.

sou'm) BOX MOUNTING.

APPLICATION FILED MAR. 25,1920.

Patented Sept. 27, 1921.

2 SHEETS SHEET 2.

N l 3140044450; V 1' g a Rhm CARL SGRABIC, 0F HEB-ANA, OHIO.

SOUND-BOX MOUNTING.

Specification of Letters Patent.

Patented Sept. 27, 1921.

Application filed March 25, 1920. Serial No. 368,495.

To all whom it may concern:

Be it known that I, CARL SoRABIo, a c1t1zen of the United States, residing at Urbana, in

the county of Champaign and State of Ohio, have invented certain new and useful Improvements in Sound-Box Mountings, of which the following is a spe-clfication.

This invention relates to improvements 1n talking machines, and has particular reference to the mechanism thereof for controlling the movements of a sound boxacross the playing face of a record, the ob ect of the invention being to provide box sup-porting means which is of such character as to cause the stylus of a sound box to travel in a straight radial path across the.face of a record during the operation of sound reproduction in order to thereby attain the.

true and correct position of the stylus in the grooves of the record and to ehmmate such scraping and scratching sounds that are ordinarily present in machlnes whereln the stylus descrlbes an are over the playing surface of a record. a a

With these and other objects in vlew, as will appear as the description proceeds, the invention accordingly consists in the novel features of construction, combinations of elements and arrangement of parts, hereinafter to be fully described and to have the scope thereof pointed out in the appended claims.

In the accompanying drawings, forming a part of this specification, similar characters of reference denote l1ke and corresponding parts:

Figure 1 is a top plan view of the tone arm mechanism employed by the present invention.

Fig. 2 is a detail vertical sectional view on an enlarged scale taken through the tone arm mounting. 1 I

Fig. 3 is a horizontal sectional viewtaken along the plane denoted by the line 3-3 of Fi Fig. 4 is a transverse vertical sectional view taken along the line 4-4 of Fig. 2.

In order that the aims and achievements of this invention may be more readily understood, it is thought juncture that the present invention particularly endeavors to improve the reproducmg cooperation between the stylus of a sound box and the grooves of a record over similar mechanisms of the prior art. Previously developed structures are usually so .formed that the tone arm has a fixed position of and in which tably well to state at this pivotal or swinging movement. This fact causes the sound box connected with its outer end to describe an arc while passing over the playing surface of a record, which results n posltiomng the stylus of such sound boxes, 1n an eccentric or offset-manner with respect to 1ts desired true vertical osition within the grooves of a record. y so offsetting the stylus, the same will frictionally engage with the sides of the grooves and hence durmg the reproduction of a record, objectionable scraping or scratching noises are invarlably present. This fact has been recogn zed' lnmany devices which attempted to eliminate such noises and these attem ts have .been mainly confined to making changes in the material stylus is formed, or by various improvements in the tone developing or amplifier structures. As a result of experimentation on this subject, it is my belief that if the needle or stylus of a sound box is caused. to travel in a straight radial path across the playing surface of a record, the needle will be properly maintained in the exact center of the record groove and hence its undue engagement with the walls of the groove will be prevented and a more favorable interpretation of the musical com osition upon the record will be rendered. desired movement onthe part of the stylus of a sound box, the present invention contemplates the provision of a talking machine wherein is embodied a horizontal rack or support v1. This rack is arranged to reswlnging tone arm 3 and 'a cooperative sound box 4, the latter being carried upon the free end of the tone arm. The tone arm 3 terminates in a downwardly directed tubular portion 5 which is adapted tobe rota- 1. To this end, the record is provided with a base block 6, preferably of hollow construction and formed from a non-metallic material. vided with achamber 7, which is in open communication with the lower end of the tone arm 3 and connects the latter for sound passage with the inlet end of an amplifier 8, the chamber 7 thus constitutes a portion' of the sound conveying conduit of the talk-- ing machine. The amplifier 8 may be of any desired construction and hence it has not been deemed necessary to illustrate and describe the same in full.

from which the 0 effect this ce1ye the usual rotatable 'turn table 2,'a

mounted in conjunction with the rack The interior of the block is pro- The upper surface of the block 6 is provided with a fixed guide plate 9, which is formed to provide a centrally located elongated slot10 in which the lower end 5 of the tone arm is slidably mounted. Further, the plate ,9 includes longitudinally disposed n p-standing flanges 11, which constitute guides for the reception of a sliding base plate 12. This plate is formed to include an upstanding circular flange 13, which is concentricallydisposed with respect to the tubular portion of the tone arm. As shown, the flange 13 is so positioned as to constitute a raceway for the reception of spaced sets of horizontally disposed ball bearings 14. The end 5 of the tone arm is, in turn, equipped with afixed collar 15 from which protrudes a beveled flange 16 of annular formation, this flange is arranged to be positioned between the spaced sets of bearings 14 and by this construction the tone arm is enabled to turn axially with but a very slight amount of pressure. This anti-friction support for the tone arm 2 is highly desirable in enabling the stylus 17 of the sound box 4 to travel freely within the grooves of a record without exercising undue friction on the latter.- A cap ring 18 is threaded upon the flange l3 and serves to maintain the bearings 14 and the tone arm 3 in their properly assembled positions.

In conjunction with the above, the stationary plate 9 or its equivalent, is provided with a fixed cam 19, in which a curved slot 20 is provided, the radius of said slot being determined by the normal tendency on the part of the stylus 17 to depart from the straight radial path when traveling across the face of a record. Cooperative with the slot 20 is a laterally projectingfinger 21 which is rigidly connected in any suitable manner with the tube 3, the outer end of said finger being provided with a roller or other anti-friction device which is ositioned to operate within the slot 20. 8b-

viously, by virtue of this construction, the

tone arm 3 will be reciprocated with respect to the base 1 during. the passage of the sound box in its normal course of operation, the extent of this movement is controlled by the radius of the slot 20 which, in turn, is calculated to cause the sound box 4 and its stylus 17 to move in the straight radial path defined b the broken line 20', shown in Fig. 1. he normal tendency of the aver age pivotally mounted tone arm is to describe the are indicated by the dotted line; 21, but owing to the construction described,

said tone arm will bebodily reciprocated during its operation, thus causing the stylus 17 to follow the path of movement iflficated by the line 20'. This results in m'afiitaining the point of a stylus in an accurately centered manner within the groove of a record, and prevents said stylus from unduly engaging with the side walls of the record record. In this instance the spring has one i of its ends fixed to the member 18, while the other or free end of the spring is engaged with the finger 21. Obviously, by the presence of the spring 22, and by means of the anti-frictionmounting for the base of the tone arm, automatic means will be provided for normally causing the sound box to travel over a record, thus relieving the record grooves of this function, a feature which also contributes to minimize friction between the stylus 17 and the record grooves.

From the foregoing description taken in conjunction with the accompanying drawings, it will be apparent that the present invention provides mechanism for causing the stylus of a sound box to travel in a straight radial ath across the playing surface of a recor thereby normally serving to properly centralize the stylus in the grooves of the record and to eliminate such undue friction that is normally caused by the unnatural engagement of the stylus with the walls of the grooves. This results in a clear and pleasing reproduction of the composition contained upon a record, and practically obliterates the scratching and grating noises that are usuall manifest in such record reproductions. he mounting for the tone arm is such as to permit the latter to freely revolve with but a minimum of friction and allows the stylus 17 to be confined to the sole operation of oscillating in accordance with the groove indentations.

What is claimed is:

1. In a talking machine, an oscillatory tone arm structure, a sound reproducer carried by the free end of said structure, and means for longitudinally shifting the positions of said tone arm durin its horizontal swinging movement across t e playing surface of a record, whereby the stylus of said reproducer will be caused to travel a substantially straight radial path across said record.

2. In a talking machine, an oscillatory knee shaped tone arm, a sound box carried. bythe free end of said tone arm and arranged for horizontal swinging movement across the playing surface of a record, a support for the tone arm, and means for longitudinally shifting said tone arm relative to its support during its horizontal swinging movement, whereby said sound box will be caused to travel in a substantially straight radial path across said record.

3. n a talking machine, a pivotally mounted tone arm, a sound box carried by the outer end of said tone arm and arranged for cooperation with the grooves of a record, means for causing said sound box to travel in a straight radial path across said record comprising a fixed cam structure, and a projection fixed to said tone arm and cooperative with said cam structure to shift the tone arm longitudinally during its oscillation.

4:. In a talking machine, a tone arm, a sliding plate connected with .the base of said tone arm, means for guiding the movements of said plate, a sound box carried by the outer end of said tone arm, a fixed cam structure, and a projection extendin from said tone arm and cooperative with sald cam structure to shift the positions of said tone arm and sliding plate during the passage of the sound box across the playing surface of a record.

5. In a talking machine, a tone arm, a sliding plate arranged to receive the lower end of said tone arm, an anti-friction bearing between said tone arm and plate, means for guiding the movements of said plate, a sound box carried by the outer end of said tone arm, a fixed cam structure, and a finger projecting rigidly from said tone arm and cooperative with said cam structure to longitudinally shift said tone arm during the movement of the latter across the playing surface of a record.

6. In a talking machine, a tone arm, a sliding member in which the base of said tone arm is received, an anti-friction bearing between said tone arm and member, a sound box carried by the outer end of said tone arm, a fixed cam structure, a finger rigidly projecting from said tone arm and cooperative with said cam structure to longitudinally shift said tone arm during the oscillation of the latter across the playing surface of a record, and resilient means cooperative with said tone arm and normally serving to revolve said tone arm across a record.

In testimony whereof I afiix my signature.

CARL SCRABIO 

